A patent document 1 discloses a known conventional valve timing control device of a vane type provided at an intake valve side.
This valve timing control device includes a housing and a vane member, wherein the housing is configured to receive a torque transmitted from a crankshaft, and includes a housing body, a front plate, and a rear plate, wherein the front and rear plates enclose corresponding axial end openings of the housing body, wherein the vane member is rotatably mounted in the housing, and is fixed to an end portion of a camshaft. The housing includes a plurality of shoes in its inner peripheral surface, wherein each shoe projects inwardly in a radial direction, wherein an advance hydraulic chamber and a retard hydraulic chamber are defined between the plurality of shoes and a plurality of vanes.
The rotational position of the vane member relative to the housing is controlled to an advance side or a retard side by selective supply and drainage of hydraulic pressure to and from the advance hydraulic chamber and the retard hydraulic chamber depending on a state of operation of the engine.
When the engine is at rest, the rotational position of the vane member relative to the housing is locked in a most retarded position by a lock mechanism provided between the housing and a vane rotor.
The lock mechanism includes a lock pin and a lock hole, wherein the lock pin is configured to travel forward and backward in a slid hole formed in a first one of the vanes and extending in an axial direction of the first vane, and wherein a distal end portion of the lock pin is configured to engage in the lock hole formed in an inner side surface of the rear plate.
The lock mechanism is subject to a problem that the lock hole, in which the lock pin engages, has a circular cross-section so that during assembling components including the housing, the vane rotor, and the rear plate, positional deviation between the lock pin and the lock hole is likely to occur due to accumulation of many factors of tolerance.
Especially, if the inner diameter of the lock hole is set small in order to enhance the precision of a clearance between the outer periphery of the distal end of the lock pin and the lock hole, and thereby suppress noise of collision between the lock pin and the lock hole due to fluttering of the vane rotor in the state where the lock pin is engaged in the lock hole, it is possible that the lock pin fails to engage smoothly into the lock hole by contact between the lock pin and the edge of opening of the lock hole due to the positional deviation between the lock pin and the lock hole.